The invention relates to missile guidance and in particular to a new and useful semi-active system of tracking for a target.
In a semi-active system of guidance, such as disclosed in German OS No. 21 62 983, for example, a target to be fought by the missile is irradiated with electromagnetic energy through an illuminator which is detached from the missile and, in general, is stationary. The radiation impinging on the target is reflected, especially also in the direction of the missile which thus passively receives information on the direction to be taken, from the relative direction of incidence of the respective portion of reflected radiation. Such a semi-active missile guidance may be effected during the entire flight or only during shorter intervals of the flight.
A basic requirement is to illuminate the target during such a semi-active phase of guidance continuously, maybe with the exception of very short interruptions.
For this purpose, systems are employed comprising on all-around search radar or a similar device for initially detecting a target. Since the antenna of a surveillance radar is directed at the target only for a short time and the radar signal is usually pulsatory, a surveillance radar is not a suitable device for illuminating the target. After all, a once detected target is illuminated by a target tracking radar having a very narrow pencil-beam directional pattern. From the echo portion reflected from a target to the target tracking radar, the instantaneous position of the target can be determined and this information can be used for pointing the narrow antenna lobe of the illuminator exactly at the target.
Since, as already mentioned, the target is to be illuminated during a semi-active phase continuously, only a single target can be illuminated in every instance by such a target tracking device. With a simultaneous lighting of a plurality of targets, i.e. a simultaneous guidance of several missiles, a plurality of target tracking devices of the same kind must be present. The multiplied costs connected thereto unfavorably affect the setting up of an effective system of guidance, since the complex, autonomous target tracking devices are very expensive.